A man who compared the Donald Trump campaign to Adolf Hitler's in the 1930s says he is glad to have started "one of the more civilised discussions" on the US presidential debate.
The tweeter, who says his name is Johan Franklin, posted a note to Americans on Friday from "the people of Germany" asking "what could possibly go wrong?" if they vote for the "guy with the loud voice", who "threatens to imprison his opponents".
The note along with the the hashtag #beentheredonethat, went viral within hours. It prompted memes equating Hitler with Trump but there was also criticism that the comparison was inflammatory.
Mr Franklin, a German citizen who works in San Diego, California, defended his "Dear America" note to the BBC.
"I know the Hitler comparison was pretty crude," he said. "It didn't have much to do with Trump himself, rather that, regardless of what he said and did, he continued to gather people behind him.
"I got frightened when trying to talk to Trump supporters within my circle of friends and colleagues and I started to see parallels to what my grandparents and other folks back home told me about what happened in Germany back in the 1930s."
The post went viral after it was shared by a Hillary Clinton supporter.